1. Field of the Invention
The present invention relates generally to wireless communication, and more particularly, to a method for supporting a User Equipment (UE) accessing Local Internet Protocol Access (LIPA) services.
2. Description of the Related Art
FIG. 1 is a diagram illustrating a structure of a System Architecture Evolution (SAE) system.
As shown in FIG. 1, a UE 101 is a terminal device for receiving data. An Evolved Universal Terrestrial Radio Access Network (E-UTRAN) 102 is a wireless access network, and includes an evolved Node B (eNB), which provides the UE 101 with a wireless network access interface. A Mobile Management Entity (MME) 103 manages a mobility context, a session context and security information of the UE 101. A Serving GateWay (SGW) 104 is primarily used to provide user plane functions, and the MME 103 and the SGW 104 may be located within the same physical entity. A Packet Data Network Gateway (PGW) 105 performs functions that include, for example, charging and lawful interception, and may be located within the same physical entity as the SGW 104. A Policy and Charging Rule Function (PCRF) 106 provides Quality of Service (QoS) policies and charging rules. The PGW 105 and the PCRF 106 are connected to an operator service network 107. A Serving General Packet Radio Service (GPRS) Supporting Node (SGSN) 108 is a network node device providing routing for data transmission in a Universal Mobile Telecommunications System (UMTS). A Home Subscriber Server (HSS) 109 is the home subscriber subsystem of UE 101. The HSS 109 protects user information including, for example, the current position of the user device, the address of the serving node, user security information, packet data context of the user device and so on.
In order to provide better service for a specific user group in a mobile communication system, multiple wireless resource management entities are usually grouped to form a Closed Subscriber Group (CSG) for the specific user group. A wireless resource management entity is a network entity for managing wireless resources and providing user device access to a wireless access network, such as, base stations in various mobile communication systems.
All users within an enterprise or a school may form a specific user group, and multiple wireless resource management entities may be grouped to form a CSG that provides dedicated access services for the specific user group.
Home eNB/Home Node B (HeNB/HNB) has been defined in current 3rd Generation Partnership Project (3GPP) subscriber systems, including, for example, open HeNB/HNB, closed HeNB/HNB and hybrid HeNB/HNB. Open HeNB/HNB does not specify any user group, and can be accessed by any user device. Closed HeNB/HNB, which is also referred to as CSG HeNB/HNB, is the HeNB/HNB in the CSG described above. CSG HeNB/HNB only permits access to user devices in a specific user group served by the CSG HeNB/HNB. A the user permitted to access a CSG is referred to as a CSG member, and a user that is not permitted to access the CSG is referred to as a non-CSG member. When Hybrid HeNB/HNB and another HeNB/HNB form a CSG, it not only permits access for the CSG member, but also permits access for the non-CSG member.
With the increased data rate for UE services, operators have provided a new technique: Selected IP Traffic Offload (SIPTO), which hands over a UE, which is in motion and is accessing a specific service, to an access point closer to the wireless access network. This hand over remarkably reduces costs of the transportation network and provides a better service experience for services with higher data rates.
3GPP proposed that a network should enable both SIPTO and LIPA.
With respect to SIPTO, when a UE accesses the Internet or other public networks via an HeNB, HNB or eNodeB/NodeB, the network may select or re-select a user plane node that is closer to the wireless access network. With respect to LIPA, a UE accesses a home network or an enterprise network via a HeNB/HNB. In a LIPA implementation, a user plane node that is closer to the HeNB/HNB, or that is in the HeNB/HNB access network may be selected or re-selected for the UE. The user plane node may be a device in the core network or a gateway. Specifically, the user plane node may be an SGW, a PGW or a Local GateWay (LGW) in the SAE system, or may be an SGSN or a Gateway GPRS Support Node (GGSN) in the UMTS system.
The network makes a determination as to whether to activate LIPA services for a UE based on UE subscription information and device capabilities of the serving base station of the UE.
The UE subscription information may include, for example, a LIPA permission parameter and a list of CSGs accessible by the UE. The LIPA permission parameter has three possible values, including LIPA_Only, LIPA_Conditional and LIPA_Prohibit.
LIPA_Only indicates that only LIPA services can be activated for the UE. When any requirement for activating the LIPA service is not met according to the UE subscription information and the device capabilities of the serving base station of the UE, the network rejects the LIPA service request of the UE.
LIPA_Prohibit indicates that the UE is not permitted to access the LIPA services. When the UE initiates a LIPA service request, if the UE subscription information is LIPA_Prohibit, the network then rejects the LIPA service request of the UE.
LIPA_Conditional indicates that when the UE initiates the LIPA service request via other base stations (e.g., a non-accessible HeNB/HNB or an eNB of the UE) and the UE subscription parameter is LIPA_Conditional, the network may select a proper PGW for the UE according to a conventional PGW selection method.
The list of CSGs accessible by the UE may include an identity of each CSG accessible by the UE and information of an Access Point Name (APN) corresponding to each CSG. Based on the combination of the above information, the network is able to determine whether the UE is permitted to access the LIPA services.
Regarding the device capabilities of the serving base station of the UE, during the process of requesting the activation of LIPA services, if an initial UE message sent to a MME by the base station includes an IP address of an LGW, it is determined that the serving base station of the UE has LIPA abilities. Otherwise, if an initial UE message does not include an IP address of an LGW, it is determined that the serving base station of the UE does not have LIPA abilities.
FIG. 2 is a diagram illustrating a method of determining whether LIPA services are to be activated for the UE.
Referring to FIG. 2, the UE requests access to the Packet Data Network (PDN) (or APN), or more specifically, the UE requests activation of the LIPA services, in step 201. The HSS identifies the list of CSGs accessible by the UE and the LIPA parameter of the APN, and identifies whether the HeNB/HNB supports the LIPA services. The list of CSGs accessible by the UE includes information on an APN accessible by LIPA services corresponding to each CSG, and the LIPA parameter of the APN includes LIPA-Only, LIPA-Prohibit, and LIPA-Conditional.
In step 203, it is determined whether the UE is a CSG member based on the information. When the UE is a CSG member the methodology proceeds to step 204. When the UE is not a CSG member the methodology proceeds to step 205.
In step 204, it is determined whether the APN is within the list of CSGs, and whether the HeNB has LIPA capabilities. The APN parameter is also determined. Further, it is determined whether to activate LIPA services according to results of the determinations.
Specifically, when the serving base station (HeNB/HNB) is in the list of CSGs accessible to the UE, when the APN requested to be accessed by the UE is the APN corresponding to the CSG, when the device capabilities of the serving base station support LIPA, and when a LIPA permission parameter of the APN requested to be accessed by the UE is LIPA-Only or LIPA-Conditional, the MME activates LIPA services for the UE.
In step 205, the APN parameter is determined and a response to the LIPA request is made according to the parameter. Specifically, when the serving base station of the UE does not support LIPA, and when the LIPA permission parameter of the APN requested by the UE is LIPA-Only or LIPA-Prohibit, the MME then rejects activation of the LIPA services for the UE.
If the serving base station of the UE does not support LIPA and the LIPA permission parameter of the APN requested by the UE is LIPA-Conditional, the MME then selects a proper PGW for the UE according to conventional PGE selection methods.
Accordingly, a UE can only access the LIPA services via a specified CSG HeNB/HNB as a CSG member. When the UE is not a CSG member, the UE can not access the LIPA services via a CSG HeNB/HNB. For example, when a UE accesses a hybrid HeNB/HNB and the UE does not belong to the CSG, LIPA services will not be activated for the UE when the UE accesses the HeNB/HNB as a non-CSG member.